Not Applicable.
This invention relates to sheet metal bending machines, and, in particular, to an open center or center-less sheet metal bending machine which forms a tear drop shape cleat, such as is used to connect sections of ductwork together to provide a tight fit for the drive cleats used in the ductwork.
Sheet metal bending machines generally have shafts which drive the element which bends the sheet metal. The use of such shafts prevents such bending machines from being used to bend sheet metal which has a length greater than the length of the opening of the sheet metal bending machine. Hence, the length of sheet metal which can be bent by such current machines is limited by the size of the opening into the machine.
Briefly stated, a center-less sheet metal bending machine is provided for forming cleats in sheet metal. The sheet metal bending machine comprises a housing having a table upon which a piece of sheet metal can be supported, a mouth through which said sheet metal can be extended, and a gap between an end of the table and the mouth. The mouth is open on its opposite ends so that the sheet metal having a width greater than the width of the bending machine can be inserted in the mouth. A clamping assembly holds the sheet metal in place. The clamping assembly comprises a stationary hold down bar, and a movable table bar having a clamping surface. The table bar is movable between an open position in which the table bar clamping surface is spaced from said hold down bar and a closed position in which said table bar clamping surface is positioned beneath said hold down bar. A table drive is provided to move the table bar between its open and closed positions. The table drive includes a link pivotally connected at a first end to an actuator and pivotally connected at a second end to the table bar, whereby, upon activation of the actuator, the link is pivoted thereby causing the table bar to move from its open position to its closed position.
In one embodiment, the actuator is a cylinder. The cylinder has a cylinder rod to which the link being pivotally connected. The cylinder rod is moved reciprocally, and, upon movement of the rod in a first direction, the table bar is moved from its open position to its closed position; and upon movement of the cylinder rod in a second, opposite direction, the table bar is moved from its closed position to its opened position.
In a second embodiment, the actuator is a cable. The link is pivotally mounted at its said first end to the housing; and the cable is connected to the link between the link""s first and second ends. When the cable is pulled, the link is pivoted to move the table bar from its open position to its closed position. In this second embodiment, a spring mechanism is provided to return the table bar to its open first position from its second position.
The position of the table bar can be adjusted to enable different gauge sheet metal to be placed in the machine. The adjustment assembly includes a table bar support and an adjustment bar. The table bar support engages the underside of the table bar. The adjustment bar is pivotally mounted in the housing and oriented generally horizontally in the housing. The adjustment bar is pivotally connected to the table bar support at a point spaced from the pivot point of the adjustment bar. The angle of the adjustment bar can be altered, thereby raising or lowering the support bar, and hence, decreasing or increasing the space between the table bar clamping surface and the hold down bar.
The machine also includes a bending assembly for forming a bend in said sheet metal. The bending assembly comprising a bending bar mounted on a rotatable member to be moveable between a start position in which sheet metal can be inserted in said machine and a finished position. The bending bar has a bending surface which engages the sheet metal to bend the sheet metal as the bar is rotated. A bending bar drive rotates the rotatable member. The rotating member is a gear segment moveable on an arced track. The gear segment and track both have the same curvature, and have a common center point. The bending bar is mounted to the gear segment to extend radially into the curvature defined by the gear segment and track such that the end of the bending bar is approximately at the common center of the gear segment and track. The track is generally circular and forms an opening which is aligned with the mouth of the housing.
The gear segment, and hence the bending bar, is driven by a drive which includes a toothed member which operatively engages said gear segment to rotate said gear segment. The toothed member comprises a toothed rack which is reciprocally driven between a first position in which said bending bar is in its start position and a second position in which said bending bar is in its finished position by a cylinder. In one embodiment, the toothed rack directly drives the segment gear.
In a second embodiment, the toothed rack engages and drives a pinion gear, which in turn drives upper and lower idler gears. The upper and lower idler gears are positioned to engage said segment gear to rotate said segment gear, and hence said bending bar.
The bending bar bending surface defines an acute angle to the horizontal and an obtuse angle with said table bar clamping surface when said bending bar is in its starting position. When the clamp is moved to its closed position; an initial bend is formed in the sheet metal which corresponds to the angle of said bending surface. Preferably, the acute angle is less then 20xc2x0. Preferably, the angle is between about 5xc2x0 and about 15xc2x0.
The machine also includes a control system. The control system is operable to activate the bending bar drive when the table bar is moved to its closed position; to activate said table drive to move said table from said closed position to its open position upon partial completion of said cleat; and to move said bending bar to said start position upon reaching said finished position.
Briefly stated, a centerless sheet metal bending machine is provided for forming cleats in sheet metal. The machine includes a housing having a table upon which a piece of sheet metal can be supported. The housing has a mouth through which the sheet metal can be extended and a gap between an end of the table and the mouth. The machine includes a clamping assembly for holding said sheet metal in place and a bending assembly for forming bends (cleats) in the sheet metal.
The clamping assembly comprises a hold down bar and a table bar having a clamping surface. The table bar is movable between an open position in which the clamping surface of the table bar is spaced from the hold down bar and a closed position in which the table bar clamping surface is positioned beneath the hold down bar. A table drive moves the table bar between its open and closed positions. The table drive includes a link pivotally connected to an actuator and to the table bar, whereby, upon activation of the actuator, the link is pivoted thereby causing the table bar to move from its open position to its closed position.
In one embodiment, the actuator is a cylinder having a cylinder rod. The link is pivotally connected at a first end to the cylinder rod and at a second end to the table bar. Upon movement of the rod in a first direction, the table bar is moved from its open position to its closed position and upon movement of the cylinder rod in a second direction, the table bar is moved from its closed position to its opened position. In a second embodiment, the actuator is a cable. The link is pivotally mounted at a first end to the housing and pivotally connected at a second end to the table bar. The cable is connected to the link between the link""s first and second ends. When said cable is pulled, the link is pivoted to move the table bar from its open position to its closed position.
The bending assembly comprising a bending bar mounted on a rotatable member. The bending bar has a bending surface which engages the sheet metal to bend the sheet metal. A bending bar drive rotates the rotatable member from a start position to a finished position to form a cleat in the sheet metal. When the table bar is in its closed position and the bending bar is in its start position, the bending bar bending surface defines an obtuse angle with the table bar clamping surface and a complimentary acute angle with the horizontal. The acute angle is preferably less than about 20xc2x0.
To enable the bending bar to rotate, the bending bar is fixed to a gear segment which is rotatably mounted in the housing. The gear segment preferably defines an arc of les than 360xc2x0, such that the gear segment will not block the sides of the housing mouth when the bending bar is in its start position. The drive includes a toothed member (preferably a piston or cylinder driven rack) which operatively engages the gear segment to rotate the gear segment. The toothed rack can directly drive the gear segment. Alternatively, the bending bar drive can include a pinion gear which is driven by the toothed rack and upper and lower idler gears driven by said pinion gear. The upper and lower idler gears are positioned to engage the segment gear to rotate the segment gear, and hence the bending bar.
The gear segment is rotatably mounted in a curved track. The curved track defines an opening which, when the bending bar is in its start position, is aligned with housing mouth. Thus, a piece of sheet metal greater in width than the width of the machine can be inserted into the machine. The gear segment and track both have the same curvature, and having a common center point. The bending bar is mounted to the gear segment to extend radially into the curvature defined by the gear segment and track such that the end of the bending bar is approximately at the common center of the gear segment and track. The track is generally circular and defines an opening which is aligned with the mouth of the housing so as to not block the sides of the mouth so that the machine can accept sheet metal having a width greater than the width of the machine.
A table bar adjuster is provided to adjust the position of the table bar clamping surface relative to the hold down bar when the table bar is in its closed position. The table bar adjuster includes a table bar support in engagement with a lower surface of the table bar and an adjustment bar pivotally connected to the table bar support at one end of the adjustment bar. The adjustment bar is pivotally mounted in the housing. When the adjustment bar is pivoted, it alters the vertical position of the table bar clamping surface relative to the hold down bar.
A control system is provided to activate the bending bar drive when the table is moved to its closed position, to activate said table drive to move the table from the closed position to its open position upon partial completion of the cleat; and to move the bending bar to the start position upon reaching the finished position.